The present invention generally relates to a locomotive and, more specifically to an adjustable cab isolator bracket for use in a locomotive cab isolation system.
Some locomotives include cab isolation systems, which detach the cab from the effects of vibration transferred by the underframe. This arrangement reduces engine induced structure-borne vibration and noise transferred into the cab.
Included in this cab isolation system is at least one pivot 122, as shown in FIG. 1, generally located near the rear of the isolated cab. The pivot 122 may be in the form of a rubber bushing. The rear pivot 122 may also be selected to control the frequency and magnitude of vertical, lateral and longitudal natural frequencies near the rear of the cab.
As shown in FIG. 1, and more particularly in FIG. 2, another component of this cab isolation system is the application of at least one coil spring arrangement in the form of a cab isolator bracket 100, 200 operatively engaging a spring 102, 202 respectively and generally located near the front of the cab. The cab isolator bracket 100, 200 and spring 102, 202 may be vertically oriented at each corner of the front of the locomotive. The cab isolator bracket 100, 200 is generally mounted to the underframe 110 of the locomotive, preferably via the short hood 112, 212. The spring 102, 202 may be in the form of any kind of spring (e.g. steel spring, coil spring, leaf spring, airbag, rubber pad, or any other comparable spring). The primary function of the spring 102, 202 is to maintain a defined stiffness in the axial direction. For example, the spring 102, 202 may be designed to tune a rigid body mode to occur at a specific frequency. Spring stiffness may be generally set to establish a cab rigid body mode (e.g. cab pitch) to occur at a frequency which is above most of the bogie suspension frequencies and the primary track input frequencies, but below underframe first bending.
Additionally, as illustrated in FIG. 2, the cab isolation system may include at least one damper 206 located near the front of the locomotive cab to be used in conjunction with the cab isolator bracket 200 and spring 202 arrangement. The damper 206 may be positioned to be along the path of the arc swing of the cab, as defined by the rear pivots (e.g., 122 in FIG. 1). The damper 206 may generally serve to reduce or eliminate magnification of low frequency motions such as those typically generated by the response of the locomotive suspension and the cab to track induced forces.
Proper cab clearance height adjustment or adjustment in the loading of the spring in a cab isolator bracket is necessary (1) to account for the build tolerance of the cab and cab application on the locomotive, (2) to assure that there is adequate clearance between the cab and the locomotive underframe to prevent another path for vibration being transferred to the cab other than at the cab isolator bracket connection points, (3) to equalize the distribution of loading on the front springs, and (4) to adjust for a break-in period of new parts. One manner of adjusting cab height or loading of the spring in a cab isolator bracket is by an application of shims to the spring arrangement until the proper cab clearance height is achieved. In traditional cab isolation systems, adjustment of cab height involves the lifting or lowering the front end of the cab in order to apply and/or remove spacer shims above and/or below each of the front springs of the isolated cab. As shown in FIG. 2, these shims (204a, 204b) are located between the spring 202 and the cab isolator bracket 200 and between the spring 202 and the underframe 210, preferably via the short hood 212.
Because adjustment of cab height has traditionally been tedious and difficult due to the necessity of lifting the entire cab and placing shims above and/or below the spring (e.g., 202), it is an object of the present invention to provide an adjustable cab isolator bracket which allows cab height adjustment without the lifting of an entire cab and without the use of shims.
It is a further object of the present invention adjustable cab isolator bracket to reduce the necessary equipment and resources required for lifting the cab. Traditionally, the crane operation for such a process would prevent others from working while the cab height is being adjusted. The present invention adjustable cab isolator bracket allows the cab height adjustment to be a more portable operation due to lack of constraint for such specialized equipment (e.g. cranes and jacks) and tooling, which allows more flexibility for the completion of the work.
An additional object of the present invention adjustable cab isolator bracket is to provide variable height adjustment features to allow more accurate height adjustment (in contrast to the fixed ⅛″ thick shims) without requiring any special skills to perform the task. The height adjustment may be performed by one person, thus allowing others to work on other areas of the locomotive. The cab height mechanism allows for only gradual lifting and lowering of the cab, thus allowing the single operator to safely control the movement of the cab. Additionally, the present invention prevents damage to the bracket by incorporating visual indicators for the operator to identify when the minimum or maximum adjustable height limit has been reached.
Moreover, because the present invention does not use shims, the cab does not need to be raised from an “at rest” position in order for the operator to reach an open gap between the cab and spring to add or remove shims. An operator may use common tools to adjust the cab height (e.g. ½″ ratchet drive, ½″ ratchet extension and wrench). Furthermore, because the present invention does not require the use of special tools or shims, there will be a reduction of parts and, as a result, a reduction in cost.
These and other desired benefits of the preferred embodiments, including combinations of features thereof, of the invention, will become apparent from the following description. It will be understood, however, that a process or arrangement could still appropriate the claimed invention without accomplishing each and every one of these desired benefits, including those gleaned from the following description. The appended claims, not these desired benefits, define the subject matter of the invention. Any and all benefits are derived from the multiple embodiments of the invention, not necessarily the invention in general.